Six on colour

Colour illusions

Look at the black dot in the middle of the red square for at least a minute. Then immediately move your eyes to the black dot in the white square. The white square will appear green. The green is the after-image of the red square. Remember: we never see what we appear to see.

The grey bar in the middle has the same colour from left to right. Take two pieces of paper and cover the top and bottom of the bar to see that it is true. Once again: we never see what we appear to see.